Breast cancer is a leading cancer killer in women of all racial and ethnic groups. Mammography has been shown to reduce breast cancer mortality by 20% to 35% in women 50 to 69. The U.S Preventive Services Task Force recommends that screening mammography begin at age 40. However, despite a lack of evidence-based guidelines, other recommendations suggest screening younger women with BRCA mutations between 25 and 30 years of age, or screening 5 to 10 years prior to the youngest age at breast cancer diagnosis in the family. Approximately one in four women under age 40 has had a mammogram. Even though mammography is widespread among younger women, evidence for how this group uses mammography is limited and fragmented. Even more limited is our understanding of racial and ethnic differences in mammography use among younger women and the effect of false positive results from early mammography. Some studies in women over 40 suggest differential responses to abnormal mammography by race and ethnicity. We must better understand how younger women across racial and ethnic groups experience mammography and whether adverse results foster avoidance or compliance behaviors later in life. This proposed study will be the first to use the National Cancer Institute's Breast Cancer Surveillance Consortium (BCSC) Data to conduct secondary data analysis examining longitudinal (1994 to 2006) mammography utilization patterns within a cohort of younger women. This application addresses NCI interest areas, including applied cancer screening, health disparities research, and surveillance research, as well as the priority areas including the impact of abnormal results on future screening behaviors, and disparities after receipt of abnormal results. The study's aims are to (1) determine whether racial/ethnic differences exist among younger women with a first mammogram before age 40, for each mammography purpose (diagnostic and screening), and (2) follow a cohort of younger women of different racial and ethnic backgrounds from an index mammogram (both diagnostic and screening) before age 40 to their first screening mammogram after age 40 to compare how women react to a false positive vs. true negative result. After the successful completion of this study, future research should target supporting younger women to navigate successfully into lifelong behaviors for the early detection of breast cancer. Evidence-based recommendations call for mammography screening to begin at age 40. However, an estimated one in four women under age 40 has had a mammogram. Our understanding of how younger women use mammography, especially by race and ethnicity, is limited and fragmented. We must better understand how younger women across racial and ethnic groups experience mammography and whether adverse results foster avoidance or compliance behaviors later in life.